1. Field of the Invention
The present invention relates to a developer cartridge for replenishing or supplying developer to a developer receiving device of an image forming apparatus, such as an electrophotographic apparatus, wherein an electrostatic latent image is formed and is then developed by the developer.
2. Related Background Art
It is known to provide a developer cartridge that may be mounted on a developer receiving device to replenish developer thereto, and which is removed from the developer receiving device after the developer has been replenished.
In some cases, such a developer cartridge has a slide lid for opening and closing a developer discharge opening formed in the cartridge. In this case, the slide lid is first opened to replenish the developer to the developer receiving device, and, after the developer has been replenished, the developer discharge opening is closed by the slide lid and then the cartridge is removed from the developer receiving device.
The developer comprises black fine powder including particles having an average volume particle diameter of about 2-20 .mu.m, and, thus, has high fluidity. Therefore, when the developer is replenished, it tends to be scattered therearound, thereby smudging the interior of the image forming apparatus and the surrounding environment.
To avoid this, a developer cartridge for replenishing developer to an image forming apparatus without scattering the developer has been proposed, as shown in FIGS. 1, 2 and 3.
Such developer cartridge comprises a container 1 for containing developer to be replenished. The container 1 is provided with a discharge opening 2 for discharging the developer. A table or plate 3 is arranged around the discharge opening 2. The table 3 is provided at its longitudinal edges with bent portions for defining guide grooves.
A plate-shaped lid 4 is mounted on the table 3 for sliding movement between a closed position where the discharge opening 2 of the container 1 is closed by the lid 4, and an open position where the discharge opening 2 is opened. The lid 4 comprises a first portion 5, and a second portion 6 hinged to the first portion 5 with a small gap therebetween.
The first lid portion 5 is provided with a notch 5a and a plurality of engagement holes 5b. The notch 5a is formed widthwise at one edge of the first lid portion 5, and the engagement holes 5b are arranged along one longitudinal edge of the first lid portion 5. A plurality of hooked projections 6a are formed on the second lid portion 6. These projections 6a are arranged along one longitudinal edge of the second lid portion 6. By engaging the projections 6a with the corresponding engagement holes 5b, the first and second lid portions 5, 6 are interconnected. The longitudinal edges of the lid 4 are inserted into the guide grooves defined by the bent portions of the table 3, so that the lid can be slid with respect to the table while being guided by the guide grooves.
As shown in FIGS. 2 and 3, a flexible film member 7 is attached to the table 3. The film member 7 is peelably adhered around the discharge opening 2 by conventional means such as heat welding, and comprises a first portion, and a second bent portion continuous to the first portion and folded back over the first portion so that it extends through the gap between the first and second lid portions 5, 6 then outwardly therefrom.
A grip 8 is attached to a free end of the bent portion of the film member 7. The grip 8 is provided with a recess 8a adapted to releasably engage with one edge of the table 3. When the grip 8 is disengaged from the table 3, the film member 7 can be withdrawn outwardly of the table 3 while sliding the lid 4, thereby opening the discharge opening 2.
However, after the developer has been loaded in the developer cartridge, the latter is moved in certain circulation paths under various environmental conditions until the developer cartridge reaches the user. In particular, under environmental conditions such as vibration, dropping, decompression or high temperature and high humidity, the first and second lid portions 5, 6 may be disconnected from each other, with the result that the film member 7 will often be peeled from the table 3.
For example, under environmental conditions such as vibration, dropping, decompression or high temperature and high humidity, the inner pressure acts on the plate-shaped lid 4 and the film member 7 which seal the discharge opening 2 of the container 1, so that the plate-shaped lid 4 will deform and swell outwardly. As a result, the first and second lid portions 5, 6 which constitute the lid 4 will be disconnected from each other. In particular, since the notch 5a is formed at the end of the first lid portion 5 in which the grip 8 is mounted, the rigidity of the end portion of the first lid portion 5 in which the grip 8 is mounted is small or weak, with the result that the connection between the first and second lid portions 5, 6 at that end portion is likely to be broken.
Further, when the connection between the first and second lid portions 5, 6 is broken, the force of the lid 4 holding down the film member 7 will decrease, such that the film member 7 is peeled from the table at a position corresponding to the disconnected area between the first and second lid portions, thus allowing the developer in the container 1 to leak.
Further, since the procedures for replenishing the developer from the developer cartridge to the developer receiving device are relatively complex and the number of such procedures are relatively great, an operator often mistakes the order of the replenishing procedures.
Furthermore, in a developer cartridge wherein the table is secured to the container by screws, the table is sometimes loosened from the container due to vibration which occurs during transportation of the cartridge. In such a case, the developer is apt to leak from the container. In addition, if the table is out of alignment with the container, it is feared that an operator's mishandling may occur.